The present invention relates to a disc drive apparatus, which is used in a mobile PC or the like, for example, and it relates, in particular, to the disc drive apparatus, upon which high shock-resistant performance is required.
The disc drive apparatus, which is mounted on the mobile PC, is required to be thin in thickness of the apparatus and to be light in weight thereof, therefore thin-sizing/light-weighting is/are essential for parts building up the apparatus. For this reason, each part is in a tendency of decreasing the rigidity thereof. On the other hand, high shock-resistant performance is required for the disc drive apparatus, and then it is necessary to ensure or keep a high reliability, in performances of recording/reproducing, even after being applied with an impact or shock thereon.
As one of factors of deteriorating the recording/reproducing performances, there is a relative tilting between an optical head and a disc. This is dominant, what is caused due to plastic deformation, being produced in the structural part by the impact or shock. In particular, a spindle motor, on which the disc is mounted within the apparatus, is attached on a unit mechanism chassis, forming an inner housing, at three (3) places of fixing positions, which are provided on a spindle motor attachment plate. Accordingly, because of the positional relationship between a supporting point, as a fixed portion, and a gravity center point of the spindle motor, a moment power acts at the position of the gravity center of the motor when the impact is applied, and deformation is generated in the spindle motor attachment plate, and therefore the disc mounted thereon inclines together with the spindle motor.
For dealing with such problem mentioned above, it is necessary to provide the structures for obtaining an increase of the rigidity against bending (i.e., a flexural rigidity), thereby reducing the deformation of the spindle motor attachment plate when the impact is applied.
In the following Patent Document 1 is disclosed the structure for preventing from the deformation, i.e., increasing the rigidity of a motor attachment portion, with providing a ring-like lib surrounding that motor attachment portion, upon a base for holding a motor that rotationally drives the disc thereon.    [Patent Document] Japanese Patent Laying-Open No. 2000-298929.